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Re: [Phys-L] kinematics objectives





John C.

A question about the below Miranda/Joey exercise that you used as an example.

In the reflection section I am quite bothered by the "final note" section where the authors tell the students what the correct answer is for their own self-reflection!

"In this context, using algebra was not the easiest."

This strikes me as reinforcing a memorize "the correct answer" mode of thought amongst students. And goes against the idea of self-reflection being a personal view based on one's own personal experience. Just curious about your opinion regarding this minor point.

Incidently, I consider this exercise to be a problem and not a conceptual question. Or at least it is a reasonable example of what I was referring to in a previous post about the use of well written problems also testing for concepts as well as problem solving ability. (in particular, in that post I suspect that a lot of the denigration of problems are really straw-man type arguments, based upon poorly written problems.)

|As to grinding through algebra, you have to know what concepts you use
|before you pick the algebra to use. I have given the Mirands & Joey problem
|to many students, and even physics teachers. Look at activity 16 at
|http://www.srri.umass.edu/mop/MOPSamples . Most can not solve it by
|algebra, but all can solve it by methods a and c. Indeed even advanced
|students, and students who have had several semesters of calculus have
|difficulty using algebra. 99% of students who have had just algebra are
|stumped. Of course I always point out that once you have the graph, you can
|write the equations, and they all agree. At that point a few students (very
|few) will actually do it. The activity is always done in class and if they don't
|have a clue about part B after 10min, they are told to move on. But some
|students have difficulty with A & C such as being able to visualize the motion.
|Some actually make Miranda's graph go past the 15m mark, so there is no
|solution. With a little prompting they eventually get it. Part A poses a
|difficulty because they have to label the markers coming back and then look at
|the numbers carefully. But once they have done this some actually use it for
|solving problems. Then they are capable of solving very difficult problems.
|